The present invention relates to the fabrication and inspection of flat workpieces in general and more particularly to the fabrication and inspection of flat articles such as flat panel display screens (FPDs) for computers, television and other suitable applications.
Flat panel visual displays such as liquid crystal displays (LCDS) are becoming increasingly popular for use in computer and television screens. However their cost remains high, in part, due to relatively low manufacturing yields.
There exist various well known techniques for FPD fabrication. Most of these techniques comprise a multi-step photolithographic process in which various thin films and photo-sensitive protective photoresist coatings are applied in turn to a glass substrate. The thin films may be metallic, non-metallic dielectric or the like depending on the particular process step. The photoresist coatings are selectively exposed, typically to UV light, developed and selectively washed away from the substrate. The thin films are etched to selectively remove regions not protected by residual photoresist. Repetition of this process deposits on the substrate a multi-layered matrix structure of metal connectors, thin film transistors, optical filters such as polarizors, and individually controllable liquid crystal cells.
Various steps in the FPD fabrication process are highly sensitive to airborne and other impurities as well as to process defects. Unfiltered air typically contains many millions of airborne particles, such as dust, per cubic meter. Conventional FPD fabrication techniques require that the maximum level of airborne particulate concentration range between 10-100 particles per cubic meter, depending on the sensitivity of the given process step.
Consequently, FPDs are typically fabricated in environments containing highly filtered air thus providing reduced contamination by airborne particles.
FPD fabrication facilities are typically situated in so-called xe2x80x9cclean roomsxe2x80x9d in which the ambient air is filtered to maintain a level of airborne particulate contamination which is at the upper end of the above-mentioned concentration range, typically at a concentration level of less than 100 airborne particles per cubic meter. This level of particulate contamination is insufficiently low for some fabrication steps. However, it is generally impracticable, because of cost and limitations on human access, to maintain large volumes of air in a clean room at the low levels of airborne particulate concentration required for such extremely contamination-sensitive fabrication steps. Consequently. FPD fabrication equipment performing steps requiring an even lower level of airborne particulate concentration typically includes a self-contained ultra clean micro-environment in which a required low level of airborne particulate concentration is maintained. Other types of FPD fabrication equipment define a micro-environment which may not differ from those of the clean room in terms of its airborne particulate concentration, but which differs in other characteristics.
In a typical FPD fabrication facility, human attendants are permitted into the clean room facilities having maximum concentration levels as low as 100 particles per cubic meter, however the attendants must be suitably dressed in protective clothing. Human attendants, even in suitable dress, typically can not access self-contained micro environments of fabrication equipment during operation thereof. Consequently, fabrication equipment operating is typically fully automated and is operational without human intervention.
It is well known to inspect FPD substrates during and following fabrication. Conventional automated inspection techniques are directed to ascertaining the uniformity of a matrix structure deposited on a glass substrate, determines whether dust has been trapped in intermediate matrix layers on the FPD, and ascertaining the performance of completed FPD panels. In addition non-automated human inspection is used to determine the existence of large scale process defects, generally visible to the human eye, such as chemical residues that have not been fully washed away, streaks, scratches and uneven exposure of the photoresist. The present invention relates to inspections of this latter type, namely large scale process defects.
Conventionally, all inspection of FPD substrates is performed in a clean room but outside the self-contained ultra-clean micro environments of the FPD fabrication equipment. A batch of substrates is typically inspected only after a series of process steps is completed. There is often a considerable time delay between the completion of a fabrication process and inspection. In the event of recurring contamination or recurring process flaws, many conventional automated system for inspecting FPD substrates during fabrication for ascertaining the uniformity of the matrix structure deposited on the glass substrate and determining whether dust has been trapped in intermediate matrix layers thereof, is commercially available from the present assignee, Orbotech Ltd. of Israel, and is designated by catalogue no. LC 3090. Part of this system is described and claimed in U.S. Patent
The existing Orbotech system described above is not normally used for identifying many typical fabrication large scale process defects on FPD substrates because it collects data relating to a matrix structure having dimensions that are orders of magnitude smaller than those of typical process defects. Moreover, because the system scans the substrates, it is physically relatively large, expensive and complex to operate.
Human inspection for process defects is conventionally performed by an operator situated inside the clean room who positions a substrate under a light source to inspect it for undesired residues, streaks, scratches and other relatively large scale anomalies on the substrate. While such inspection can be useful to detect certain large scale fabrication process defects, it takes place outside the self-contained micro environment of contamination-sensitive process equipment and it suffers from the typical high cost and non-standardization associated with non-automated human inspection methods.
Other types of inspection, typified by the disclosure of U.S. Pat. No. 5,771,068, assigned to the present assignee and incorporated herein by reference, are conventionally used to inspect FPDs that are sufficiently completed to enable selective activation of pixels. According to an embodiment described in U.S. Pat. No. 5,771,068, various combinations of pixels are illuminated and a relatively low resolution staring array sensor images the entire substrate as the various combinations are illuminated. The images are analyzed for variations in intensities. This type of inspection is clearly not suitable for inspection FPD substrates in intermediate stages of fabrication.
Additional publications that are believed to be relevant to the art of inspecting for large scale defects and non-conformities on surfaces of articles include U.S. Pat. No. 5,640,237 and Japan Patent Application 11-94753.
The present invention seeks to overcome drawbacks of conventional FPD inspection systems and to provide an improved system and method for automated inspection of FPDs and other flat surfaces.
The present invention further seeks to provide an FPD manufacturing system having increased yield.
The present invention still further seeks to provide an automated system for inspecting FPDs which is less expensive and more compact in size than conventional automated scanning FPD inspection systems.
Additionally the present invention seeks to provide a system operative to inspect FPD substrates inside the self-contained ultra-clean micro environment of equipment performing contamination-sensitive FPD fabrication processes.
One aspect of a preferred embodiment of the invention relates to a system and method for the manufacture of FPDs using contamination-sensitive fabrication equipment having a self-contained micro environment typically, but not necessarily, characterized by an airborne particulate concentration that is substantially lower than that of its surroundings. Automated inspection apparatus is provided inside the self-contained micro environment of the process equipment and FPD substrates are inspected inside the micro environment of the fabrication equipment before transportation to other fabrication equipment to perform a downstream fabrication process.
Another aspect of a preferred embodiment of the invention relates to the inspection of FPD substrates that is performed inside fabrication equipment immediately following the completion of a series of fabrication process steps and before the substrate is transferred to other fabrication equipment to perform a subsequent series of steps. A determination of whether there exist any process defects on the substrate is made in order that the operation of the process equipment that is performing defective steps can be interrupted and corrected before a recurring defect affects subsequent substrates.
Another aspect of a preferred embodiment of the present invention relates to a system and method for FPD fabrication in which FPD substrates are inspected for typical fabrication process defects by an automated system. Preferably, the inspection is performed without comparison to an external reference. Preferably, inspection is provided to detect typical fabrication process defects including scratches, process residues, uneven exposure of photoresist, uneven deposition of films and contamination by particles embedded in the substrate.
Another aspect of a preferred embodiment of the present invention relates to a system to automatically inspect substantially flat surfaces of industrial articles, such as FPD substrates, for the existence and absence of relatively large scale process defects such as are generally visible to the human eye. Relatively large scale process defects include, by way of example only, in the context of FPD substrate inspection: uneven deposition of coatings, uneven removal of coatings, rinse residues, chemical residues, incomplete exposure of a photo-resist deposited on the substrate, scratches, lines, and particles embedded in the substrate.
Preferable, various configurations of illumination are applied to a surface under inspection, and for each configuration of illumination an image of an illuminated region on the surface is acquired using a sensor, preferably a staring array CCD sensor.
The types and configurations of illumination used in the context of preferred embodiments of the present invention generally include: Bright Field Illumination, in which a specular reflection of light from the source of illumination impinges on a lens associated with a sensor viewing the object; and Dark Field Illumination in which a specular reflection of light from the source of illumination does not impinge on a lens associated with a sensor viewing the object. Additionally the bright field and dark field illumination respectively may be diffuse or focused.
Thus for example, diffuse substantially bright field illumination or diffuse dark field illumination may be applied. Diffuse substantially bright field illumination refers to illumination in which a diffuse illumination source is used, and the mutual orientation of the surface under inspection, the illumination source and a lens associated with the sensor is such that the specular reflection of at least some of the light from the diffuse source impinges on a lens associated with the sensor. Diffuse dark field illumination refers to illumination in which a diffuse illumination source is used, and the mutual orientation of the surface under inspection, the illumination and a lens associated with the sensor is such that a specular reflection of light from diffuse source does not impinge directly on a lens associated with the sensor.
Additionally, focussed bright field illumination or focussed dark field illumination may be applied. Focussed bright field illumination refers to illumination in which the illumination is focussed to form a beam which is intersected by the surface under inspection, wherein orientation of the surface under inspection, the illumination and the sensor is such that a specular reflection of light from the focussed source impinges on a lens associated with the sensor. Focussed dark field illumination refers to illumination in which illumination is focussed to form a beam which is intersected by the surface under inspection, wherein orientation of the surface under inspection, the illumination and the sensor is such that a specular reflection of light from the focussed source does not impinge on a lens associated with the sensor.
It is appreciated that the surfaces of some articles inspected, for example FPDs, may include a periodic spatial feature that forms a diffraction grating. In the context of inspecting surfaces having such a periodic spatial feature, focussed dark field illumination is further categorized into on-axis and off-axis focussed dark field illumination. Focussed on axis dark field illumination refers to focussed dark field illumination in which the illumination source, the surface under inspection and the sensor are oriented such that the zero""th, or central, order of diffraction does not impinge on a lens associated with the sensor, however some other non-zero""th order of diffraction impinges on a lens associated with the sensor. Focussed off-axis dark field illumination refers to focussed dark field illumination in which the illumination source, the surface under inspection and the sensor are oriented such that no orders of diffraction impinge on a lens associated with the sensor, preferably because mutual axes along which diffraction orders converge are all outside the lens associated with the sensor.
Another aspect, of a preferred embodiment of the present invention relates to a system to inspect coatings applied to substantially flat surfaces of industrial objects, in which the coatings are applies, and subsequently inspected in using the apparatus and methods of the present invention.
There is thus provided in accordance with a preferred embodiment of the present invention a system for manufacture of flat panel displays including a plurality of manufacturing devices located in a first controlled environment, at least some of the plurality of manufacturing devices each including an enclosure defining a second controlled environment different from the first controlled environment, and a plurality of optical inspection devices operative to inspect flat panel display substrates at various stages of the production thereof by the plurality of manufacturing devices, at least some of the plurality of optical inspection devices being located within the enclosures defining the second controlled environments.
Preferably the first controlled environment is an airborne particle controlled environment having a first level of controlled airborne particulate contamination, and the second controlled environment is an airborne particle controlled environment having a second level of controlled airborne particulate contamination that is less than the first level of controlled airborne particulate contamination.
Further in accordance with a preferred embodiment of the present invention the plurality of optical inspection devices are operative in coordination with the plurality of manufacturing devices for inspecting the substrates prior to transfer thereof out of the second controlled airborne particle contamination environment.
Still further in accordance with a preferred embodiment of the present invention the at least some of the plurality of optical inspection devices include non-scanning sensors.
Additionally in accordance with a preferred embodiment of the present invention the plurality of optical inspection devices are operative to identify fabrication process defects occurring during production of flat panel display substrates.
Moreover in accordance with a preferred embodiment of the present invention the process defects include at least one of the following: uneven deposition of coatings, uneven removal of coatings, rinse residues, chemical residues, incomplete exposure of a photo-resist deposited on the substrate, cratches, lines, and particles embedded in the substrate.
Further in accordance with a preferred embodiment of the present invention the each of the plurality of optical inspection devices includes at least one non-scanning sensor which views substantially all of the surface of the substrate.
Still further in accordance with a preferred embodiment of the present invention the at least one non-scanning sensor includes a plurality of non-scanning sensors, each sensor viewing a portion of the substrate and together the plurality of sensors viewing substantially the entire surface of the substrate.
Additionally in accordance with a preferred embodiment of the present invention each of the plurality of optical inspection devices includes an illuminating array operative to provide various combinations of illumination.
Moreover in accordance with a preferred embodiment of the present invention the combinations include at least dark field and substantially bright field illumination.
Further in accordance with a preferred embodiment of the present invention the non-scanning sensor acquires at least one image of the substrate for each combination.
Still further in accordance with a preferred embodiment of the present invention the system also includes an image analyzer for identifying process defects by computer, analysis of a plurality of images of the substrate taken under various ones of the combinations of illumination.
Additionally in accordance with a preferred embodiment of the present invention, the image analyzer is operative without comparison to an external reference.
Moreover in accordance with a preferred embodiment of the present invention, the enclosure contains a first plurality of illuminators mounted on a first wall of the enclosure and a second plurality of illuminators mounted on a second wall of the enclosure, orthogonal to the first wall.
Further in accordance with a preferred embodiment of the present invention, the system also includes directionally adjustable illuminators.
Still further in accordance with another preferred embodiment of the present invention there is provided an inspection system for use in inspecting flat panel displays including a non-scanning optical array for viewing a flat panel display substrate, and an illumination subsystem sequentially providing dark field and bright field illumination of the flat panel display substrate when the optical array views the flat panel display substrate.
Additionally the illumination subsystem provides various combinations of dark field and bright field illumination of the flat panel display substrate when the optical array views the flat panel display substrate. The dark field and said bright field illumination may be diffuse or focussed.
Moreover, the flat panel display substrate may have a surface that includes a periodic spatial feature that is operative to diffract said dark field and said bright field illumination.
Further in accordance with a preferred embodiment of the present invention, the system includes a spatially positionable stage to support the flat panel display substrate, and the stage spatially positions the substrate at various angles relative to the illumination subsystem.
Still further in accordance with a preferred embodiment of the present invention, the optical array, illumination subsystem and stage are configured and arranged to selectively enable viewing the flat panel display substrate such that a non-zero""th order of diffraction impinges on the non-scanning optical array. Preferably, a multiplicity of the non-zero""th orders of diffraction of a similar order impinge on the non-scanning optical array.
Additionally, the optical array, the illumination subsystem and the stage are preferably configured and arranged to enable selectively viewing the flat panel display substrate such that a zero""th order of diffraction impinges on the non-scanning optical array.
Moreover, the optical array, the illumination subsystem and the stage are preferably additionally configured and arranged to enable selective viewing of the flat panel display substrate such that substantially no orders of diffraction impinge on the non-scanning optical array.
Preferably, the optical array, the stage and the illumination subsystem are configured and arranged to sequentially view the flat panel display substrate such that in one view a selected non-zero""th order of diffraction impinges on the optical array, and in other each sequential views at least one of the following orders of diffraction impinges on the optical array: a zero""th order of diffraction, an additional selected non-zero""th order of diffraction, no order of diffraction, the same non-zero""th order of diffraction of a different region of the article.
Additionally, in accordance with a preferred embodiment of the present invention the system also includes an image analyzer receiving an output from the non-scanning optical array and being operative to detect process defects including at least one of: uneven deposition of coatings, uneven removal of coatings, rinse residues, chemical residues, incomplete exposure of a photo-resist deposited on the substrate, scratches, lines, and particles embedded in the substrate.
Further in accordance with a preferred embodiment of the present invention the optical array views substantially all of a surface of the substrate. Alternatively, the optical array views only part of the surface of the substrate
Still further in accordance with a preferred embodiment of the present invention the optical array acquires at least one image of the substrate for each of a plurality of different illuminations.
Additionally in accordance with a preferred embodiment of the present invention the image analyzer identifies the defects by computer analysis of a plurality of images of the substrate taken under differing illumination.
Moreover in accordance with a preferred embodiment of the present invention the system also includes an enclosure containing a first plurality of illuminators mounted on one wall thereof and a second plurality of illuminators mounted on a second wall thereof.
Further in accordance with a preferred embodiment of the present invention the system also includes a third illuminator mounted on a third wall of the enclosure.
Still further in accordance with a preferred embodiment of the present invention the system also includes a diffuser associated with the illumination subsystem.
Moreover in accordance with a preferred embodiment of the present invention the system includes a light source and a reflector operative to provide concentrated light from the light source to at least part of said flat panel display substrate.
Preferably, the reflector has two points of focus, and wherein a projector is situated at a first of points of focus, and the second point of focus is situated away from the flat panel display substrate. The reflector is preferably a section of an ellipsoid.
Alternatively, the reflector is flat and is operatively associated with a lens, which is preferably a fresnel lens attached to the reflector.
Moreover, in accordance with an additional alternative, the system includes light source, preferably a projector, and a lens operative to provide concentrated light from the light source to at least part of said flat panel display substrate. Preferably, the projector is situated at a first focus of the lens, and a second focus of the lens is situated away from the flat panel display substrate.
Additionally in accordance with a preferred embodiment of the present invention the system includes an adjustable mounting assembly for selectably determining at least one of relative inclination, spatial separation and axial orientation of at least two of the optical array, the illumination subsystem and the substrate.
There is also provided in accordance with a preferred embodiment of the present invention an inspection system for use in inspecting objects including a non-scanning optical array for viewing an object, and an illumination subsystem sequentially providing dark field and bright field illumination of the flat panel display substrate when the optical array views the object.
Further in accordance with a preferred embodiment of the present invention the illumination subsystem provides various combinations of dark field and bright field illumination of the object when the optical array views the surface. Preferably, the dark field and said bright field illumination are diffuse or focussed.
Moreover, the surface may include a periodic spatial feature that operative to diffract light impinging thereon.
Additionally, the system preferably includes a spatially positionable stage to support the article, wherein the stage spatially positions the article at various angles relative to the illumination subsystem, and the optical array, illumination subsystem and stage are configured and arranged to selectively enable viewing the surface such that a non-zero""th order of diffraction impinges on the non-scanning optical array.
Additionally, the system is preferably arranged so that multiplicity of non-zero""th orders of diffraction of substantially the same order impinge on the non-scanning optical array. Preferably, the optical array, the illumination subsystem and the stage are configured and arranged such that the surface may be selectively viewed while a zero""th order of diffraction reflected from the surface impinges on the non-scanning optical array, or while no orders of diffraction impinge on the non-scanning optical array.
Preferably, the optical array the illumination subsystem and the stage are configured and arranged to sequentially view the article so that one view of the article a selected non-zero order of diffraction impinges on the optical array, and in other sequential views at least one of the following orders of diffraction impinges on the optical array: a zero""th order of diffraction, an additional non-zero""th order of diffraction, the same non-zero""th order of diffraction of a different region of the surface of the article, and no order of diffraction.
Still further in accordance with a preferred embodiment of the present invention the system also includes an image analyzer receiving an output from the non-scanning optical array and being operative to detect process defects including at least one of: uneven deposition of coatings, uneven removal of coatings, lines residues, chemical residues, incomplete exposure of a photo-resist deposited on the substrate, scratches, lines, particles.
Additionally in accordance with a preferred embodiment of the present invention the optical array views substantially all of a surface of the substrate. Alternatively, the optical array views only part of the surface of the substrate.
Moreover in accordance with a preferred embodiment of the present invention the optical array acquires at least one image of the substrate for each of a plurality of different illuminations.
Further in accordance with a preferred embodiment of the present invention the image analyzer identifies the defects by computer analysis of a plurality of images of the substrate taken under differing illumination.
Still further in accordance with a preferred embodiment of the present invention the system also includes an enclosure containing a first plurality of illuminators mounted on one wall thereof and a second plurality of illuminators mounted on a second wall thereof.
Additionally in accordance with a preferred embodiment of the present invention the system also includes a third illuminator mounted on a third wall of the enclosure.
Moreover in accordance with a preferred embodiment of the present invention the system also includes a diffuser associated with the illumination subsystem.
Additionally in accordance with a preferred embodiment of the present invention, the system includes a light source and a reflector operative to provide concentrated light from the light source to at least part of said surface. Preferably, the reflector has two points of focus. A projector preferably is situated at a first focus, and a second focus is situated not on the surface.
Further, in accordance with a preferred embodiment of the present invention, the reflector is a section of an ellipsoid. Alternatively, the reflector is flat and is operatively associated with a lens, which is preferably a fresnel lens attached to the reflector.
Alternatively, the system includes a light source, preferably a projector, and a lens operative to provide concentrated light from the light source to at leas; part of the flat panel display substrate. Preferably, the projector is situated at a first focus of the lens, and a second focus of the lens is situated not on the flat panel display substrate.
Further in accordance with a preferred embodiment of the present invention the system includes an adjustable mounting assembly for selectable determining at least one of relative inclination, spatial separation and axial orientation of at least two of the optical array, the illumination subsystem and the substrate.
There is also provided in accordance with a preferred embodiment of the present invention apparatus for optically inspecting the surface of an article having a substantially planar surface, including an inspection region, an illuminator operative to selectably illuminate the surface of an article located in the inspection region with at least two predetermined configurations of illumination, an image acquisition sub-system including at least one non-scanning camera for acquiring images of the surface of the article when illuminated by at least one predetermined configuration of illumination, and an image analysis subsystem for computer analyzing the images and detecting anomalies in the surface as a function of variations in reflected intensities of illumination. Based on the results of analysis of the surface, the article may be discarded, or subjected to further processing. Further processing may include correction of anomalies.
There is additionally provided a spatially positionable stage for supporting the article in the inspection region in selectable orientation relative to the illumination apparatus.
Moreover, in accordance with a preferred embodiment of the invention the image analysis subsystem is operative to identify anomalies that are substantially the same size as the resolution of the camera.
There is additionally provided in accordance with a preferred embodiment of the present invention apparatus for coating an article having a substantially planar surface, including a coating generator operative to generate a coating on a surface of the article, an illuminator for selectably illuminating the surface bearing the coating with at least two predetermined configurations of illumination, an image acquisition sub-system including at least one non-scanning sensor for acquiring images of the surface of the article for each combination of illumination, and an image analysis subsystem for analyzing the images and detecting anomalies in the surface on the basis of variations in reflected intensities of illumination.
There is also provided in accordance with a preferred embodiment of the present invention apparatus for inspecting an article in a clean room, including an inspection device situated in the clean room and including an inspection stage selectably positionable by remote control, at least one non-scanning sensor viewing the substantially the entire inspection stage, an array of illuminators illuminating the inspection stage, automated feed apparatus, a control station situated outside the clean room, the control station including a viewer for viewing articles placed in the inspection device and a controller for positioning the stage and providing selected configurations of illumination to illuminate the article.
There is also provided in accordance with a preferred embodiment of the present invention a method for manufacture of flat panel displays including providing a plurality of manufacturing devices located in a first controlled environment, at least some of the plurality of manufacturing devices each including an enclosure defining a second controlled environment different from the first controlled environment, and inspecting flat panel display substrates at various stages of the production thereof by the plurality of manufacturing devices at a location within the enclosures defining a second controlled environment.
Further in accordance with a preferred embodiment of the present invention the inspecting step includes inspecting the substrates prior to transfer thereof out of the second controlled airborne particle contamination environment.
Still further in accordance with a preferred embodiment of the present invention the inspecting step includes inspecting using non-scanning sensors.
Additionally in accordance with a preferred embodiment of the present invention the method further includes identifying fabrication process defects occurring during production of flat panel display substrates.
Moreover in accordance with a preferred embodiment of the present invention the identifying step includes identifying process defects including at least one of the following: uneven deposition of coatings, uneven removal of coatings, rinse residues, chemical residues, incomplete exposure of a photo-resist deposited on the substrate, scratches, lines, and particles embedded in the substrate.
Further in accordance with a preferred embodiment of the present invention the inspecting step includes inspecting using at least one non-scanning sensor which views substantially all of the surface of the substrate.
Still further in accordance with a preferred embodiment of the present invention the inspecting step includes inspecting using a plurality of non-scanning sensors, each sensor viewing a portion of the substrate and together the plurality of sensors viewing substantially the entire surface of the substrate.
Additionally in accordance with a preferred embodiment of the present invention the inspecting step includes illuminating the substrate with an illuminating array operative to provide various combinations of illumination.
Moreover in accordance with a preferred embodiment of the present invention the combinations include at least dark field and substantially bright field illumination.
Further in accordance with a preferred embodiment of the present invention the inspecting step includes acquiring at least one image of the substrate for each combination using the non-scanning sensor.
Still further in accordance with a preferred embodiment of the present invention the method also includes performing computer analysis of a plurality of images of the substrate taken under various ones of the combinations of illumination to detect process defects.
Additionally in accordance with a preferred embodiment of the present invention the image analysis step is performed without comparison to an external reference.
Moreover in accordance with a preferred embodiment of the present invention the providing step includes further mounting a first plurality of illuminators on a first wall of the enclosure and mounting a second plurality of illuminators on a second wall of the enclosure, orthogonal to the first wall.
Further in accordance with a preferred embodiment of the present invention the mounting step includes further providing directionally adjustable illuminators.
There is also provided in accordance with a preferred embodiment of the present invention a method for inspecting a flat panel display substrate including viewing a flat panel display substrate using a non-scanning optical array, and sequentially illuminating the flat panel display substrate with dark field and bright field illumination while the optical array views the flat panel display substrate.
Further in accordance with a preferred embodiment of the present invention the sequentially illuminating step illuminates using various combinations of dark field and bright field illumination of the flat panel display substrate when the optical array views the flat panel display substrate.
Still further in accordance with a preferred embodiment of the present invention the method also includes receiving an output from the non-scanning optical array, and detecting process defects including at least one of: uneven deposition of coatings, uneven removal of coatings, lines residues, chemical residues, incomplete exposure of a photo-resist deposited on the substrate, cratches, lines, and particles embedded in the substrate.
Additionally in accordance with a preferred embodiment of the present invention the viewing step includes viewing substantially all of a surface of said substrate.
Moreover in accordance with a preferred embodiment of the present invention the viewing step includes acquiring at least one image of the substrate for each of a plurality of different illuminations.
Further in accordance with a preferred embodiment of the present invention the detecting step includes identifying the defects by computer analysis of a plurality of images of the substrate taken under differing configurations of illumination.
Still further in accordance with a preferred embodiment of the present invention the method also includes providing an enclosure containing a first plurality of illuminators mounted on one wall thereof and a second plurality of illuminators mounted on a second wall thereof.
Additionally in accordance with a preferred embodiment of the present invention the providing step also includes providing a third illuminator mounted on a third wall of the enclosure.
Moreover in accordance with a preferred embodiment of the present invention the method also includes providing a diffuser associated with the illumination subsystem.
Further in accordance with a preferred embodiment of the present invention the method also includes providing an adjustable mounting assembly for selectably determining at least one of relative inclination, spatial separation and axial orientation of at least two of the optical array, the illumination subsystem and the substrate.
There is also provided in accordance with a preferred embodiment of the present invention a method for inspecting objects including viewing an object using a non-scanning optical array, and sequentially illuminating the object with dark field and bright field illumination while the optical array views the object.
Further in accordance with a preferred embodiment of the present invention the sequentially illuminating step illuminates using various combinations of dark field and bright field illumination of the object while the optical array views the object.
Still further in accordance with a preferred embodiment of the present invention the method also includes receiving an output from the non-scanning optical array, and detecting process defects including at least one of: uneven deposition of coatings, uneven removal of coatings, rinse residues, chemical residues, incomplete exposure of a photo-resist deposited on the substrate, cratches, lines, and particles embedded in the substrate.
Additionally in accordance with a preferred embodiment of the present invention the viewing step includes viewing substantially all of a surface of the object.
Moreover in accordance with a preferred embodiment of the present invention the viewing step includes acquiring at least one image of the object for each of a plurality of different illuminations.
Further in accordance with a preferred embodiment of the present invention the detecting step includes identifying the defects by computer analysis of a plurality of images of the object taken under differing configurations of illumination.
Still further in accordance with a preferred embodiment of the present invention the method also includes providing an enclosure containing a first plurality of illuminators mounted on one wall thereof and a second plurality of illuminators mounted on a second wall thereof.
Additionally in accordance with a preferred embodiment of the present invention the providing step also includes providing a third illuminator mounted on a third wall of the enclosure.
Moreover in accordance with a preferred embodiment of the present invention the method also includes providing a diffuser associated with the illumination subsystem.
Further in accordance with a preferred embodiment of the present invention the method also includes providing an adjustable mounting assembly for selectably determining at least one of relative inclination, spatial separation and rotational orientation of at least two of the optical array, the illumination subsystem and the object.
There is also provided in accordance with a preferred embodiment of the present invention a method for optically inspecting the surface of an article having a substantially planar surface, including defining an inspection region, selectably illuminating the surface of an article located in the inspection region with at least two predetermined configurations of illumination, for each predetermined configuration of illumination acquiring an image of the surface of the article using at least one non-scanning camera, and analyzing the image and detecting anomalies in the surface as a function of variations in reflected intensities of illumination.
There is additionally provided in accordance with a preferred embodiment of the present invention a method for coating an article having a substantially planar surface, including generating a coating on a surface of the article, selectably illuminating the surface bearing the coating with at least two predetermined configurations of illumination, for each configuration of illumination acquiring an image of the surface of the article using at least one non-scanning sensor, and analyzing the images and detecting anomalies in the surface on the basis of variations in reflected intensities.
There is also provided in accordance with a preferred embodiment of the present invention a method for inspecting an article in a clean room, including situating an inspection device in the clean room, selectably positioning an inspection stage of the inspection device by remote control, viewing substantially the entire inspection stage using at least one non-scanning sensor of the inspection device, illuminating the inspection stage using an array of illuminators of the inspection device, placing articles in the inspection device using automated feed apparatus of the inspection device, and situating a control station outside the clean room, the control station including a viewer for viewing articles placed in the inspection device and a controller for remotely positioning the stage and providing selected combinations of illumination.
There is additionally provided in accordance with a preferred embodiment of the present invention a method for inspecting the surface of an article, including the steps of placing the article in an inspection region defined by a stage, illuminating a portion of the surface of the article with at least one configuration of dark field illumination, acquiring an image of substantially the entire surface for the at least one configuration of dark field illumination, illuminating the surface with at least one configuration of substantially bright field illumination, acquiring an image of substantially the entire surface for the at least one configuration of substantially bright field illumination, and providing computer analysis of the images to determine non uniformities in reflected intensities.
Further in accordance with a preferred embodiment of the present invention the at least one configuration of dark field illumination includes a plurality of dark field illumination configurations, and a separate image is acquired for each configuration.
Still further in accordance with a preferred embodiment of the present invention the at least one configuration of substantially bright illumination includes a plurality of bright field illumination configurations, and a separate image is acquired for each configuration.
Additionally in accordance with a preferred embodiment of the present invention each predetermined combination of illumination is provided by selecting a predetermined inclination and rotational orientation of the substrate, and separate images of the surface are acquired for each inclination and rotational orientation.
Moreover in accordance with a preferred embodiment of the present invention there is provided an additional step of optically treating the illumination prior to acquiring an image.
Further in accordance with a preferred embodiment of the present invention the treatment is provided by optical filters.
Still further in accordance with a preferred embodiment of the present invention the filters filter for selected wavelengths.
Additionally in accordance with a preferred embodiment of the present invention the filters filter for selected polarization.
Moreover in accordance with a preferred embodiment of the present invention the surface is illuminated with a selected combination of broad spectrum illumination and imaged through an optical filter operative to transmit light in a first predetermined spectral range, and subsequently imaged through and optical filter operative to transmit light in a second predetermined spectral range.
Further in accordance with a preferred embodiment of the present invention the surface is illuminated with a first combination of illumination through an optical filter operative to transmit light predetermined spectral range and imaged, and subsequently illuminated with a second combination of illumination through an optical filter operative to transmit light in a second predetermined spectral range and imaged.
Still further in accordance with a preferred embodiment of the present invention the surface is illuminated with a selected combination of broad spectrum illumination and imaged through and optical filter operative to transmit light having a first polarization state, and subsequently imaged with through a second optical filter operative to transmit light having a second predetermined polarization state.
Additionally in accordance with a preferred embodiment of the present invention the surface is illuminated with a first combination of optically filtered illumination having a first predetermined polarization state and imaged, and subsequently illuminated with a second combination of optically filtered illumination having a second predetermined polarization state and imaged.
Moreover in accordance with a preferred embodiment of the present invention there is provided an additional step of blurring the image during acquisition.
Further in accordance with a preferred embodiment of the present invention an image is blurred by introducing, during image acquisition, relative movement between at least two of the following: the surface, the camera, and an optical element between the surface and the camera.
Still further in accordance with a preferred embodiment of the present invention there is provided a further step of analyzing the non-uniformities in reflective intensity with a computer to determine the presence of defects in coatings on the substrate.
Additionally in accordance with a preferred embodiment of the present invention the article is a flat display panel substrate.
There is also provided in accordance with a preferred embodiment of the present invention a method for coating the surface of an article, including the steps of depositing a coating on at least part of a surface of the article, placing the article in an inspection region, illuminating a portion of the coated surface of the article with dark field illumination and acquiring an image of the illuminated surface, illuminating the surface with substantially bright field illumination and acquiring an image of the illuminated surface, and analyzing each image with a computer to determine non uniformities in reflected intensity.
There is also provided in accordance with a preferred embodiment of the present invention apparatus for the automatic optical inspection of a generally flat article having at least one generally periodic spatial feature, comprising a light beam generator providing an illuminating beam of light along an illuminating light beam axis onto a generally flat article having at least one at least generally periodic spatial feature; and a sensor viewing the article along a light receiving axis disposed at an angle with respect to the illumination light beam axis whereby a generally non-zero""th order of diffracted light reflected from the said article impinges on the sensor.
Further in accordance with a preferred embodiment of the present invention, there is provided a selectably orientable support supporting the generally flat article, and a postioner for changing the angular inclination of the generally flat article with respect to the illumination light beam axis and said light receiving axis during viewing by the sensor.
Preferably, the positioner is operative to selectably orient the generally flat article so that it lies in a plane that is not always perpendicular to the plane defined by the illuminating light beam axis and the light receiving axis.
Still further in accordance with a preferred embodiment of the present invention, there is provided a light absorbing housing enclosing at least said light beam generator and the sensor for generally preventing diffuse illumination from impinging on said sensor is also provided.
There is also provided in accordance with a preferred embodiment of the present invention a method for manufacturing flat panel displays including the steps of providing a first controlled environment in which an airborne particle controlled environment having a first level of controlled airborne particulate contamination, and a second controlled environment in which an airborne particle controlled environment having a second level of controlled airborne particulate contamination is less than the first level of controlled airborne particulate contamination.
Further in accordance with a preferred embodiment of the present invention the method of inspecting a flat panel display includes illuminating the dark field and the bright field illumination are diffuse. Prefrably, the dark field and the bright field illumination are focussed.
Additionally in accordance with a preferred embodiment of the present invention the flat panel displays substrate has a surface that includes a periodic spatial feature, and the dark field and the bright field illumination are diffracted by the spatial feature.
Still further in accordance with a preferred the optical array, illumination subsystem and stage are configured and arranged to selectively enable viewing the flat panel display substrate such that a non-zero""th order of diffraction impinges on the non-scanning optical array. Additionally a multiplicity of the non-zero""th orders of diffraction of a similar order impinge on said non-scanning optical array.
Still further in accordance with a preferred embodiment of the present invention, the method for inspecting the flat panel display includes configuring and arranging the optical array, the illumination subsystem and the stage to additionally enable selectively viewing the flat panel display substrate such that a zero""th order of diffraction impinges on the non-scanning optical array. Additionally, the optical array, the illumination subsystem and the stage are configured and arranged to additionally enable selective viewing of the flat panel display substrate such that substantially no orders of diffraction impinge on the non-scanning optical array.
Furthermore, the optical array and the illumination subsystem are configured and arranged to sequentially view the flat panel display substrate and wherein in one view a selected non-zero""th order of diffraction impinges on the optical array, and in other each sequential views at least one of the following impinges on the optical array: a zero""th order of diffraction, an additional selected non-zero""th order of diffraction, no order of diffraction, the same non-zero""th order of diffraction of a different region of the article.
The method for inspecting a flat panel display includes providing a light source and a reflector operative to provide concentrated light from the light source to at least part of said flat panel display substrate. Additionally the reflector has two points of focus, and wherein a projector is situated at a first of points of focus, and the second point of focus is situated away from the flat panel display substrate. The reflector may be a section of an ellipsoid. Alternatively, the reflector may be flat and operatively associated with a lens, and the lens may include a fresnel lens attached to the reflector.
Furthermore the method for inspecting a flat display panel may include providing a light source and a lens operative to provide concentrated light from the light source to at least part of the flat panel display substrate. Additionally the projector is situated at a first focus of the lens, and a second focus of the lens is situated away from the flat panel display substrate.
In a method for inspecting a flat display panel the dark field and the bright field illumination may be diffuse. Additionally, the dark field and the bright field illumination may be focussed, and the surface includes a periodic spatial feature operative to diffract light impinging, thereon.
The method also includes providing a spatially positionable stage to support the article, wherein the stage spatially positions the article at various angles relative to the illumination subsystem. Additionally, the optical array, illumination subsystem and stage are configured and arranged to selectively enable viewing the surface such that a non-zero""th order of diffraction impinges on the non-scanning optical array, and the multiplicity of non-zero""th orders of diffraction of substantially the same order impinge on the non-scanning optical array. Furthermore, the optical array, the illumination subsystem and the stage are configured and arranged to additionally enable selectively viewing of the surface such that a zero""th order of diffraction impinges on the non-scanning optical array. Furthermore, the optical array, the illumination subsystem and the stage are configured and arranged to additionally enable selectively viewing the object such that substantially no orders of diffraction impinge on the non-scanning optical array. The optical array, the illumination subsystem and the stage are also configured and arranged to sequentially view the object and wherein in one view a selected non-zero order of diffraction impinges on the optical array, and in other sequential views at least one of the following impinges on the optical array: a zero""th order of diffraction, an additional non-zero""th order of diffraction, the same non-zero""th order of diffraction of a different region of the surface of the article, and no order of diffraction.
Additionally the optical array views only a part of a surface of the substrate.
The method for inspecting a flat panel display also includes providing a light source and a reflector operative to provide concentrated light from the light source to at least part of said surface wherein the reflector has two points of focus, and wherein a projector is situated at a first focus, and a second focus is situated not on the surface.
The reflector is a section of an ellipsoid or alternatively the reflector may be flat and is operatively associated with a lens. The lens may be a fresnel lens attached to the reflector.
The method for inspecting a flat panel display also includes providing a light source and a lens operative to provide concentrated light from the light source to at least part of the flat panel display substrate, and a projector which is situated at a first focus of the lens, and a second focus of the lens is situated not on the flat panel display substrate.